You know I've been watching this thread and it occurs to me that the Sonofresco is just a bigger version of a hot air popper.
My Uber-tweaked out Poppery 1 can roast 1/2 # of green. It has an adjustable heater and an adjustable fan that was boosted to 130volts.
I did not build it, but I swapped out a number of 1400 watt Popcorn Pumpers and a couple of stock P1's a couple of years ago.
I have a Programmable Hottop, but I find it easier to roast with the P1, go figure!
I have the schematics and information in my home computer, I'll look for it when I get home tonight. Maybe you electrical engineers can figure a way to hybridize the 2. Using propane for the heat source and using an adjustable fan motor seems the way to go for 2 to 5 # batches.
John, do you remember Eddie K from the GCC, a few years back he built a really great version!
Gary